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[Jeremy Cole <jeremycole@xxxxxxxxxx>]

Maria developers/captains,

Prior to posing it as a final patch contribution or opening a JIRA ticket,
I wanted to propose this idea.

The attached patch adds what amounts to compile-time checking for unmatched
DBUG_ENTER/DBUG_LEAVE (DBUG_RETURN, DBUG_VOID_RETURN) by introducing a
variable in DBUG_ENTER which is only used in DBUG_LEAVE. This allows any
compiler which can robustly detect unused variables to detect the mismatch
at compile-time. There is already a run-time check for this case, but it is
somewhat limited as it requires _db_return_ to be called in order to detect
the mismatch, and this is in practice not always the case. Particularly
three cases allow this to escape detection:



   1. Some instrumented functions are called only from non-instrumented
   functions.
   2. Some instrumented functions are called only from non-returning
   functions, such as abort or die functions.
   3. Some instrumented functions are called from functions who call my_end
   or my_thread_end (making cs unavailable) before returning.

In any case please see the attached DRAFT patch for a full implementation
of the idea. Note one bit of ugliness is that non-returning functions,
after this patch, must be marked explicitly as DBUG_ENTER_NO_RETURN -- this
actually is not really a bad thing, though in and of itself.

Regards,

Jeremy

Attachment: dbug_missing_leave_unused_variable.patch
Description: Binary data